1. Field of the Invention
The present invention relates to a peanut processing apparatus, and more particularly, to an apparatus and method for separating peanuts, which have an undesirable aflatoxin content and other light undrainable apparatus, by means of a fluidized bed.
2. Discussion of the Related Art
Aflatoxin is a carcinogen produced by a fungus which is commonly found in peanuts. Although not always visible from the outside, Aflatoxin affects the density of the peanut. A peanut afflicted with aflatoxin may also develop a hollow center.
Conventional separation techniques have proven unsatisfactory for separating the affected peanuts. These techniques are not sufficiently sophisticated to allow separation of peanuts having density differences as low as 10 percent. Nevertheless, as stricter aflatoxin regulations are implemented, it has become necessary to develop an apparatus and method which is capable of making such fine separations.
Since aflatoxin-affected peanuts are lighter and less dense than non-affected peanuts, it has been suggested to separate such affected peanuts using a water flotation technique. While this technique has allowed more sophisticated separation than conventional techniques, water flotation techniques yield water-logged peanuts which must subsequently be dried. This added drying step, of course, adds an extra cost to the peanuts and results in lower quality peanuts.
It has also been suggested to split the peanuts in half, thereby exposing the aflatoxin fungus itself. The aflatoxin affected peanuts could then be separated using conventional sensor equipment. While this technique allows for a very sophisticated separation, it adds an extra cutting step which increases the manufacturing cost. Also, it is unsatisfactory where whole peanuts are desired. Further, many commercial applications require peanuts which have not been split. For these applications, the splitting technique is not commercially viable.
Fluidized beds have been used previously for specific gravity separation. Forsberg (U.S. Pat. No. 2,928,545) discloses a gravity separator for separating grain from light particles, such as chaff, and heavy particles, such as stones. A mixture of grain and foreign particles is fed onto an oscillating deck, and air is fed through the deck to cause the materials to separate according to density. Extremely high density materials, such as stones, fall to the perforated screen and are conveyed upwardly to be discharged at the upper end portion of the deck. The lighter materials are conveyed toward the lower end of the deck, where a skimmer removes the light, undesirable materials.
Gravity separators have also been used for separating foreign material from peanuts. Examples of such gravity separators include Carter et al. (U.S. Pat. No. 2,429,343), Hobbs (U.S. Pat. No. 3,400,84), Paul (U.S. Pat. No. 2,449,007), Solomon, Jr. et al. (U.S. Pat. No. 162,392). While these separators have satisfactorily separated stones and other heavy material from peanuts and have separated very light material from peanuts, these techniques are not satisfactory for separating material which differs only slightly from the weight of the desired peanuts. Thus, they cannot be employed to separate aflatoxin affected peanuts from desirable product.